PURPOSE: To mechanically certainly coat the end surface of a plate body, by forming an end surface at a coated plate body, placing said plate body in a paint, removing a coating film and then coating said end surface.

CONSTITUTION: The front and back main surfaces 2 of a steel plate 1 are coated with coating films, and a desired workpiece W is formed by punching at the coating part 4. Hence, the workpiece W in which the end surface of the steel plate 1 and that of the coating film are formed on the same plane without difference in level is obtained. By dipping said workpiece W in paint, the paint adheres onto the end surface of the steel plate 1. Thereafter, it is dried. Thus, the end surface is mechanically efficiently coated without the need to perform the step of brushing or wiping with waste.